1. Field of the Invention
The present invention relates to discharge nozzles used in pouring ladles for controlling the flow of molten metal from the ladle.
2. Description of Related Art
In the steel industry, molten steel was traditionally dispensed from a large vat-like ladle. The ladle was traditionally equipped with a nozzle at a bottom location thereof which controlled the flow of molten steel out of the ladle. Conventional nozzles included a bore through which the molten steel flowed, and a stopper rod assembly that was used to restrict the flow of molten steel through the nozzle. The stopper rod assembly typically had a vertical rod that was covered with a refractory material and that extended upward through the interior of the ladle. A mechanical linkage that was attached to the top portion of the rod was used to raise and lower the stopper rod. The bottom end of the stopper rod was adapted to engage the bore in the nozzle as the stopper rod was lowered, thus restricting the flow of metal through the nozzle. The flow of steel through the nozzle was initiated by actuating the mechanical linkage to lift the stopper rod out of engagement with the bore in the nozzle, thus permitting the molten steel to flow.
It was found to be difficult, however, to precisely control the flow of molten steel in ladles having nozzles and stopper rod assemblies as described above. The stopper rod extended through the interior of the ladle between a linkage at the top of the ladle to the nozzle at the bottom of the ladle, and thus was very long. Because of the length of the stopper rod, it was found to be difficult to open and close the valve with precise control. In addition, because the stopper rod extended throughout the interior of the ladle, and was surrounded by molten steel, it was subject to rapid erosion.
There is therefore a continuing need for improved ladle nozzles. In particular, a nozzle that is efficient to manufacture, has fewer parts, and is more controllable is desirable. In addition, a nozzle having interchangeable components to accommodate different flow rates and that is more resistant to erosion is also desirable.